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jak_E_lee

oh dear....dead vetta!

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well,got this vetta maybe 2 months ago as a few of you here know and,i will say,a lot of you guys using the FB vetta 2 users group page will know me.

Amps been great over these 2 months until last night.....

I noticed it wasnt sounding good so..inspected it today...its down a speaker(its the 2x12 combo)

So,initially thought dead speaker.Swapped wires over between speakers and its dead on a feed heading for the speaker.

Unscrewed it to make sure a wire had not fell off inside but all was good.

Memory flashed it in the hope this would be the fix(lost all my own patches as I had no way to back em up) but to no avail.

So,really its only half a vetta now and I suspect eventually this will go too.

As someone who gig,s regularly...cant use this amp and here in good old Northern Ireland, there is no L6 repair centres.

So...dont know what my next step is to get it fixed.I do suspect it as a power amp fail.Had always noticed when it was turned on i always got a thud sound from it but then I had other amps that have done the same too.

Kinda lost here what the next step is or is that my vetta relationship over and sell it on as spare parts now on ebay?

I really dont want to go down the sell it on road and would prefer a fix up and get it back out doing gigs as its a great sounding amp.

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well,got this vetta maybe 2 months ago as a few of you here know and,i will say,a lot of you guys using the FB vetta 2 users group page will know me.

Amps been great over these 2 months until last night.....

Even if you aren't I'm sure you can find a competent electronics technician who can likely fix it for you. I have the service manual in pdf format if he needs it. I'm sure there's somebody in Belfast.  With the schematics, and common test equipment almost any decent technician can likely put it right for you. Most of the parts are common electronic components so can be sourced and replaced, only a few parts are specific to the amp and are scarce as hens teeth if available at all. 

I'm in the facebook group too. 

 

 I noticed it wasnt sounding good so..inspected it today...its down a speaker(its the 2x12 combo)

So,initially thought dead speaker.Swapped wires over between speakers and its dead on a feed heading for the speaker.

Unscrewed it to make sure a wire had not fell off inside but all was good.

Memory flashed it in the hope this would be the fix(lost all my own patches as I had no way to back em up) but to no avail.

So,really its only half a vetta now and I suspect eventually this will go too.

As someone who gig,s regularly...cant use this amp and here in good old Northern Ireland, there is no L6 repair centres.

So...dont know what my next step is to get it fixed.I do suspect it as a power amp fail.Had always noticed when it was turned on i always got a thud sound from it but then I had other amps that have done the same too.

Kinda lost here what the next step is or is that my vetta relationship over and sell it on as spare parts now on ebay?

I really dont want to go down the sell it on road and would prefer a fix up and get it back out doing gigs as its a great sounding amp.

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If it truly is an amp issue I would bet that any competent amp tech that works on solid state stuff could sort it out. It's the things that make a vetta a vetta that would be hard to source. But z power amp issue should be common.

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If it truly is an amp issue I would bet that any competent amp tech that works on solid state stuff could sort it out. It's the things that make a vetta a vetta that would be hard to source. But z power amp issue should be common.

I have found a L6 repair centre in england so will make a call on monday and take it from there.

heaphones work fine in the amp so its for sure,a power amp related issue,blown capacitor perhaps,could be small problem but causing big ones for me as I am a gigging musician.

will update this post after I speak to L6 uk

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there might still be an authorized service center somewhere....

but the main UK Line6 location has closed, and service support goes here now:

 

YAMAHA Music Europe GmbH 
Siemensstrasse 22-34 
25462 Rellingen
Germany

 
Tel: +49 (0) 4101 303 0
Fax: +49 (0) 4101 303 333

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I have found a L6 repair centre in england so will make a call on monday and take it from there.

heaphones work fine in the amp so its for sure,a power amp related issue,blown capacitor perhaps,could be small problem but causing big ones for me as I am a gigging musician.

will update this post after I speak to L6 uk

Could it be something so simple as a fuse. Maybe each power amp side has a separate external or internal fuse. I know I'm kinda grasping at straws but you never know. And with the headphone jack still working yes it does seem like a power amp section problem. Keep us updated and good luck.

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Sorry but the power supplies are common to both channels so if the PS fails both channels would likely be out.

 

The output split between the headphone/direct outs and the power amp is from DSP 2, U36. There the data splits from separate pins on the DSP U36. The serial data out from pin 11 goes to U21 a digital to analog converter (DAC) for the headphone and direct out circuits. The serial data output from DSP U36 pin 12 goes to U20 an identical DAC as chip U21 and is used to drive the power amps.

 

My guess would be a blown FET in the defective channel or perhaps one of the opamps between the DAC and the output power FETs.

 

As I said any competent tech along with the service manual and common test equipment should be able to sort the amp out for you. It's a heavy beast to be shipping around but that's your call. Look online or in the local phone directory for shops that repair stereo gear and such and they can likely help you. Ask specifically if they can troubleshoot and isolate faults down to the component level and they are not board swappers as most so called service centers are. A board swapper won't be of much use as replacement PCBs are not likely to be found.    

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i basically said the same thing right after you... because your post was quoted weirdly and i couldnt make out what part was you and what part was close...

but yeah... you got it... should be fixable.

 

Sorry but the power supplies are common to both channels so if the PS fails both channels would likely be out.

 

The output split between the headphone/direct outs and the power amp is from DSP 2, U36. There the data splits from separate pins on the DSP U36. The serial data out from pin 11 goes to U21 a digital to analog converter (DAC) for the headphone and direct out circuits. The serial data output from DSP U36 pin 12 goes to U20 an identical DAC as chip U21 and is used to drive the power amps.

 

My guess would be a blown FET in the defective channel or perhaps one of the opamps between the DAC and the output power FETs.

 

As I said any competent tech along with the service manual and common test equipment should be able to sort the amp out for you. It's a heavy beast to be shipping around but that's your call. Look online or in the local phone directory for shops that repair stereo gear and such and they can likely help you. Ask specifically if they can troubleshoot and isolate faults down to the component level and they are not board swappers as most so called service centers are. A board swapper won't be of much use as replacement PCBs are not likely to be found.    

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Well there a a couple of clues that should help the tech. One is that since one channel is OK that means that the irreplaceable part concerned, the DSP is likely OK too.

 

I think you mentioned a thump when you turned the amp on, that's a bit of a concern since there is a circuit that delays and ramps up power to the power amp intended to reduce this. That symptom would point you to a failed FET.

 

If the tech does find a bad FET, it's a good idea to replace both or all power FETs in the affected channel and to also look closely at the power related components around the bad FET and replace as necessary. The FETs are IRFP250N from International Rectifier. The datasheet for these is online in many places and the parts are in current production.  

 

When replacing old components, like polarized caps, more is better. Large polarized caps tend to fail with age and a bad FET can also burn out resistors in the power supply to them.

 

Good thing it didn't blow out a speaker too as the speakers were custom made for the Vetta.    

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In the morning,I am ringing E&M in Milton Keynes,UK as they are the only place to appear on a search as official yamaha/line 6 specialists.

My pal had a spider amp repaired by them when the output died and its been fine since they fixed it and turn around was quick(7 days)

I looked inside the amp today for a blown cap but all looked good inside visually,no scorch marks,nothing.

Im not that tech minded but i put an ohm meter on the speaker cables and both were worlds apart in reading.

The defective side reading real low in the 20k setting and I could only get a reading on the good side in the 200k setting.

I dont think there is much wrong with,it just needs the right man to look at it who knows what to do

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Ok..I am updating this after a long time as some of you guys probably do not use the FB user group.

I left the amp in a repair shop and 2 weeks later..they still had not looked at it so I took it from them and thought..I shall have a go myself,whats to loose cos I cant get anyone to look at it.

Got out my DMM and found differing resisitance values on each speaker output so alarm bells are ringin!

Removed the power amp and measured the field transistors as instructed by dickfoster here and those were the culprit.

Theres 4 on the vetta power amp so @ £1.24 each from CPC,I bought 4 of them and replaced with new ones and the amps been pretty reliable since.Only had one small issue since with a dirty pot but its went well since the repair

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Also,thanks dickfoster for your help on this repair.

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Also,thanks dickfoster for your help on this repair.

Glad to help and glad you got your Vetta back into action. 

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I have gone to play my duoverb head through my line 6 4x12 and....no sound. Gutted....power showing at pilot light but no lights on the amp model indicators. Any suggestions guys? 

 

Thanks

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